Safety appliance for motors.



P. R. FORMAN.

SAFETY APPLIANCE FOR MOTORS.

APRPLIOATION FILED N0I.23,1909;

980,090, v Patented Dec. 27, 1910.

UNITED STATES PATENT OFFICE.

PARIS B. FORMAN, OB CHICAGO, ILLINOIS, ASSIGNOR TO THEIEURDE'IT-ROWN']IIHZP MANUFACTURING COMPANY, OF CHICAGO, ILLINOIS, ACORPORATION OF ILLINOIS.

SAFETY APPLIANCE FOR MOTORS.

Specification of Letters Patent.

Application filed November 23, 1909. Serial No. 629,602.

rushes of current.

A further object of the invention is to provide means which are simpleand efficient whereby, in starting up a motor it is protected by a fuseof large capacity, and, after starting], a fuse of smaller capacity isautomatica laced in the motor circuit.

Other 0 jects of the invention will appear more fully hereinafter.

The invention consists substantially in the construction, combination,location, and relative arran ement of parts, all as will be morefullyiereinafter set forth, as shown in the accompanying drawing, andfinally pointed out in the appended claims.

The drawingshows in diagrammatic elevation an arrangement of motorsafety appliance embodying my invention, as applied a three-phasealternating current motor. V

It is a usual custom to protect motors from injury due to excessivesupply of current, by the use of safety fuscsl In the case of (11* .rectcurrent motors it is also customary to employ a starting resistance totake care of the first rush of current in starti 'up the motor, thecurrent, in starting up t e motor tors,

heing'lmuchgreater than is required to oper-. ate t e motor after it hasattained its nor; mal speed. This initial rushof current in starting themotoris even more pronounced in alternating current motors than withdirect current motors. In certain types of alternating current motors itis also feasible to employ starting resistance to protect the motorwindings against injur from-the first rush of current in starting testartin resistance in the case of both direct and. alternating currentmotors being grad'ually cut outas the build up their own resistancethrough the evelopment of counter-c eanemotive force, while attainintheir in rmal speed of operation.- In certain tyes-c mes-- However, itisv not practice. letouse. any starting resistzmeeo'r currentrestricting.

means, and in such cases dependence nu. be had on the fuses to protectlllGJlHfl'I i'm from injury. In any case, whether starting resistance isemployed or not, should tilt! motor get stuck, or get out of order, orhe overloaded, or for other reason should be unable to create its normalcounter-electromotive force, or its normal resistance, or should fail toattain its normal speed, the fuses employed are required to be of suchlarge capacity to stand the large initial flow of current, and hence areof such capacity that the windings of the motor are burned out beforethe fuse will act.

It is among the special purposes of: the present invention to providemeans whereby in starting up the motor it is protected against the largeinitialflow of current, but a ter' the lapse of a controllable intervalof time a fuse of-smaller capacity is automatically introduced intocircuit thereby protecting the windings of-the motor from injury due toa continued supply of unduly large current.

While the safety a liances embodying my invention are capae of use inconnection with motors employing startin" resistances, they arespecially applicable to motors of the type where starting resistancesare not used, or in place of starting resistances, and. moreparticularly in connection with alternating currentmoto'r's.

In the drawing reference signG, designates a motor which is. shown to beof the three-phase alternating current type though my invention, asdefined in the claims, is not to be restricted or limited to a motor ofthis t' e.

is the main switch for controlling the supply of current tothe motor. Inth1sinstance the main switch controls each of the three wires, 4:, b,-c, of thethree wire system. In the main current supply circuit is a fuseA, of large capacity designed to carry the large volume 0 currentrequired to start the motor. -In-the case illustrated, a large fuse A isincluded in each of "the. three wire circuits. I p

B desi ates auxiliary fuses of small capacity. n accordance with myinvention so that said aux? arc inch-lifter; in

the. motor cilcu Mini-cling pro- Li'ctililh to the motor which it is notpossible to secure from the fuses of lurgc (:u 'mcity. any specificallydill'crcntmenus may be oxzzploycd to effect the short circuiting ol the:zuxllifirj. fuses anti the muommtic rupture of such short Circuits butof said short circuits shou'u'] In cil'vcicrl uulw matically andpreferably nficr the. lapse of a prr-de'niomnincd ouit (ikQi-JYJllillflUintcrvul o1 liizicnfler tin: np in ll'lUlJJl circuit has been closed Iprefer to operate the short ciruniiing dcviccsof lhu Kilian-y fuses bycurrent supplied. by the closing; of the main switch.

In the particular (llJlI'UdlHltfHb oi. my in VGlltiOIl which I hurt sccted for illustration of the principles:- involved I employ n solenoidH, arranged to he energized by current supplied irom either one or moreof the circuit wires a, b, c. The core or plunger K, or the solenoidoperates o lever D, carrying the contactstrips 1*, which are insulatedtherefrom and fyvhlch control 'the short circuitsof the 'ziuxi'liarfuses -B. 'It will. be observed that the so enoid core or plungerconnected to the lerecD through a pin and slot connection, the solenoidcore '01 plunger havingan elon ated slot- E, for this purpose, wherebythe ever D remains in pos tion for the contacts} to maintain the shortcircuits of fuses B, closed until after thejlapse of. an intervlii oftime follo'wii igv jithecl0sing of the solenoid circuit. In order tocontrlol and regulate this'intcr vul of time as may be required;zi'piston L, is com-lected to thmsolcnorii plunger K. and," operatesin-Q hsvin a stop;,; {0 cock'lwl to regulate the exhaust of :ur therehereby regulating the speed ofrn-ovenent of the solenoid or plungcrinto'the coil, and hcnce controlling the length of] time current is suppliedto the motorfan air dash pot cylinder from, c

.46 thngjil gh the barge-fuses before the, fuses of sma erccpac1ty-.=$1;e lacedin :ci rcuit;j. .I1 1 notice the slot E fan the aircock M, o'fthe ash pot' are so relative-1y ad'usted that the length ofti ne the iiises A, o lar e capacit stein service; below the fuses ofsum.

- 1 mp s are enable euro 1' under-normaliconclitions to .attaiujits'norninl' speed and jtobuildyup its .oonxitervelctro-motive' fo'rce. If,however} .tlie jnotoi-should be'out-o'f order, dnfshould :be overloaded,"of-should get stuck, a r-otherw thin pencil-M ume, tlteoperaitlon of.

v flteapgotatus is suoh't-het'the fuses of small] '92: poor tarenutomaticclly 'cut into circuit and hence will bo Working relation-t0-br'eak ltll'o motor circuit and therefore pre voat'ciamageto e'motor.

cc the. breaking 5 vision as new anti useful, cm] of my own inwntion:nni desire to secure hy Letters Patent is:---

1. In a safety appliance for motors the combination with a motor, of afuse of large capacity in the circuit thereof, an auxiliary fusc ofsmaller mpucily and means operated by Lin, current supply in thevircuitof the fuse of largo cu 'iucit i'or imroclucing said auxiliaryl'usc into the nmlor circuit.

i 2. The combination with a motor, of u I use of large capacity in hell'lOiUl circnii,

I an). uuxiliary fuse of small capacity-aim) alrrnngcrl in the motorcircuit, a short circuit for said auxiliary fuse, and means operated bythe current supply in. the circuit of the fuse of large'capacity forbreaking said short circuit.

The combination with a motor, of a fuse of large capacity in the motorcircuit, an auxiliary fuse of small capacity also arranged in the motorcircuit, a short circuit for the auxiliary vfuse, and means operated bycurrent inthc motor circuit for breaking said short circuit.

4. The combination with a motor of a fuse of large capacity in the motorc1-rcuit,.-an auxiliary fuse of small capacity, means op eluted by theclosing of the motor-circuit for including the auxiliary fuse in themotor circuit, and means for controlling ;the time interval between the'closingof the motor circuit and the introduction of the auxiliary useintothe'motor circuit. *1 5. The combination wit-he motor of afuse ,oflarge capacity-in e motor circuit, an

niuxiliary-iuso'df smell capacity also in ,the

ond for controlling the timeiit which sa id shortcircuit breakin meansoperates.

6, The combination wit '9, motor,o a fuse, of large "capacity in themotor circuit, an oiixiliary fuse of'smal-l capscit also in the 'iiiotorcircuit, ashort circuit or said auxil'u ry fuse, a solcnoiti-for'braking. said shortcircuit, and means for controlling the t on of thesolenoid. a 'lfi circuit, is ample ,to

, 77 The combination with a motor, of a'fu se 'auxilia'r y" fuseof'smnll-cupacity also in the "motor circuit, 'a' short circuit for thenuxiliary fuse, 'a solenoidior'breaking said short circuit, and i cla'shactionof'th'e so'l'cncig :iuxilig'ry ii-use o'f" smjall capacity; alsoin the rnoto'r circuit, a shortcucuit for the auxilmltyfuse, alevcrjorcontrollingsald short lerer. i 9', The combination with a motor,of z fuse rno'torcircuit,-z i shortcircuit for t-ho nu: 1liary.fus e,-rneans.opersteo by current 11; the:- motoncu cuitior breaklng saidshort circuit,

oil-largocapaicity in the motoncirc'uityan' pot ion controlling the -8;The combination with a motor, of a fuse of large capacity in the-motorcircuit, at!

circuit,-,cnd a solenoid focopcrating the fuse of large capacity in themotor circuit, an auxiliary fuse of small capacity also in the motorcircuit, a shortcircuit for the aux-' iliary fuse, alever forcontrolling said short circuit, a solenoid operated by current in themotor circuit, and a lost motion connection between the solenoid andlever.

11. The combination with a motor, of a fuse of large capacity in themotor circuit, an auxiliary fuse of small capacity also in the motorcircuit, a short circuit for the auxiliary fuse,

'a lever for controlling said short circuit, a

solenoid, a pin and slot connection between the solenoid plunger andsaid lever, and a dash pot for regulating the movement of the solenoidplun er.

In testimon wiereof I have'he'reunto set my hand in t 1e presence of thesubscribing witnesses, on this eighteenth day of N overnher A. D., 1909.

v PARIS :R.- FORMAN.

Witnesses: J. G. MITCHELL, L. M. SHIELDS.

